


a secret under the sea

by Silverine



Category: Voltron: Legendary Defender
Genre: Established Relationship, Fluff, I guess? haha, M/M, MerMay 2018, Scuba Diving, Secret Identity
Language: English
Status: Completed
Published: 2018-05-14
Updated: 2018-05-14
Packaged: 2019-05-06 06:11:57
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,890
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/14635727
Author URL: https://archiveofourown.org/users/Silverine/pseuds/Silverine
Summary: Meeting Matt that night at the beach changed Shiro's life forever, and he is sure there's nothing in this world that could separate him from his perfect boyfriend. Until he goes scuba diving that fateful day...





	a secret under the sea

**Author's Note:**

  * For [Kunfetti](https://archiveofourown.org/users/Kunfetti/gifts).



> This is for kunfetti, who gave me this cute prompt! Thank you and please check her shatt fics too, they're awesome!  
> Also, I used one of May's prompts from Shatt Sunday Challenge! Too bad the title of this one sucks so much, though, sorry haha. Enjoy!

One year ago, Takashi Shirogane was just a (forcedly) retired marine trying to cope with the loss of his arm, with a disguised can of beer in his hand, sitting at night on the beautiful beach a friend recommended as “a healing place”. The moon was out and the beach was empty, far from the noise of the nightlife, with only a few occasional passersby here and there. Takashi had chosen a covert spot to sit, watching the waves and hearing the calming sounds of the sea, sweet like a lullaby. His friend had been right, the place was so relaxing he even forgot why he was so depressed for a while, without thinking about anything in particular, until he spotted in the sand at some distance what seemed to be a dark bunch of clothes and glass. Curious, wondering if someone had forgotten them earlier, he stood up and approached the pile of things, discovering a huge open bag, its contents half spread in the sand, including weird instruments, notebooks and glass jars, accompanied by a lonely pair of jeans hurriedly tossed near them. Frowning, he looked around to see if there was someone to whom these things could belong, but the beach was empty. Worried, starting to fear the worst, he scanned the sea surface. Nothing. What if the owner had drowned? He crouched to search in their things something to identify them, when a voice shouted:

“Hey! That’s mine!”

He looked up and saw a young man walking towards him, coming from the sea itself. He was only wearing an oversized shirt, hanging heavily from his dripping body. For some reason, Takashi gulped at the sight of his long, slim and pale legs stopping right in front of him.

“What are you doing?” asked the man. He bent down to hurriedly get his things at the same time Takashi stood up, startled.

“S-sorry, I just thought the owner may had had an accident and wanted to check if there was any name or number…”

The drenched man looked up with an eyebrow raised, but then his eyes stopped right in front of Takashi’s legs. He blinked a few times as if he couldn’t believe what he was seeing, and then shook his head, looking at him in the eyes.

“Oh. Uhm, I see, thanks. Sorry for yelling at you, then,” the boy was starting to blush and then he saw his jeans lying in the sand. His wet face burned. “Oh my gOD I’M NOT WEARING PANTS. SORRY I FORGOT…”

Takashi felt himself blush too and half turned around to let him get dressed, stifling a laugh. The guy was weird and he should be leaving, but curiosity was stronger.

“So, can I ask where did you come from? I’ve been here for a while and didn’t see you,” said Takashi. The man seemed to freeze and Shiro dared to take a look. He had his pants on, but they were now soaking wet, like the rest of himself.

“Right. I was taking some samples. I was, uh… distracted, I guess. I felt like swimming,” he explained. In fact, that didn’t explain much, but Shiro was nervous so he let it pass.

“I see. Are you a student?” he asked, judging the man’s young features.

“More like an investigator. I work for Altea College… you know, the campus up there?” the man answered, showing the distant lights from the huge building on top of a hill. It was a renowned college, and Takashi nodded.

“I see. Well, then… be careful. The waves are strong around here,” he said, waving goodbye. His stomach was still tense, he noticed.

“Wait! Uhm, I’m… I’m sorry for being so rude to you earlier. I want to apologize… would you like to grab some coffee on the way back? Or maybe something else…” the man was eyeing the can in Takashi’s hand. He crushed it unconsciously. He never was a good drinker, and wished he didn’t have the evidence right there, especially in front of such a pretty person.

The man’s hair was wet, but it was pale and shiny under the moonlight, framing a manly face with big, light eyes, and decorated by a warm smile. He had a scar on his cheek, and Shiro wondered if that was why his presence made such a strong impression, as if he was the mysterious protagonist of a fantasy novel. Or maybe it was just that lean, graceful body. Under the moonlight, even in his huge, soggy clothes, he looked beautiful. Again, Takashi gulped before answering.

“Coffee is alright. But… shouldn’t you change first?”

“Oh. Yeah, I guess you’re right. If you don’t mind making a stop… I live near here,” the man replied.

“Sure. I’m staying near here too,” said Shiro. Knowing that they lived close to each other (at least for now) was making his stomach flutter.

“Yeah… Yeah! Great. By the way, the name’s Matthew Holt, but you can call me Matt,” said the young man, shaking his bag, sand falling from it.

“Takashi Shirogane. But you can call me Shiro,” he said, helping him to put his scattered things inside the bag.

“Cool name for a cool guy,” smiled Matt, and that’s when Shiro knew he was lost.

 

* * *

  
One year later, Takashi is a new man. He has definitely moved to the small town, near the beach. Motivated, he uses his prosthetic arm with pride, started working for Altea College as a coach and has found a new passion: scuba diving, all thanks to his beautiful, resourceful and supportive boyfriend Matt. Their romance has been like a bestseller with no angst, an absolute dream. After that first meeting, a month later Takashi was stuttering about his feelings and Matt was blushing and leaping right into his arms for all answer. From there on, just kisses and roses.

They really have no important problems, except for one thing: schedule incompatibility. When Matt has his “special assignments”, that can mean that he’ll be back one day later, or even a week later, and it’s infuriating how he never has signal on his cellphone the entire time he is gone.

This time it has been three days and Shiro finds himself sighing, watching the sea from his rented house window, wondering if living together could help to control this uncomfortable longing. Knowing that Matt would come back directly to _their_ house instead of _his_ house would be really, really nice…

He discusses this issue with his scuba instructor, Lance, while both are checking the equipment for the day and finish suiting themselves. The cheerful Cuban is Matt’s friend and an expert love counselor, or at least he says so, though Shiro isn’t so sure about that.

“So, in short… you wanna tie the knot with our Matty?” he asks, wiggling his eyebrows. Shiro blushes.

“N-no. I mean, yes? But not yet, for now I’d just like to… have him home. I don’t know,” Shiro sighs.

“Oh man, he got you good. That’s fine, no shame in that,” laughs Lance, patting his student’s broad back. But then, he looks at the sea, and adds: “But I would wait a bit for that. I think you… you should wait until you know Matt better, you know?” 

“What do you mean?” Shiro is frowning, and Lance gets nervous.

“Uh… It’s just, you see… the guy is different, right? Kind of a, uhm… free soul. There are some things you may need to learn about him first, I don’t think rushing things will do you any good. Maybe you should wait until he… asks you to move himself? Hey, seriously, wait!”

Shiro decides to go ahead and throw himself into the water. Lance, pissed, hurries to finish putting on his gear and do the same, but Shiro is giving his strong legs good use, and is already diving away. The silent peace of the sea isn’t enough to ease him this time, but it helps a bit.

Yeah, sure, Lance is Matt’s good friend, but he is his boyfriend and he knows _everything_ about him. True, some things are a bit obscure. Like his family. He knows about his parents and sister, but doesn’t have a single picture of them. Weird. And sure, maybe he doesn’t get the kind of work Matt does for Altea College, though he really is well loved there. And, ok, maybe he finds a bit odd some of his eating preferences, his sudden impulses to go and bathe on the sea, and the fact that his best friend is a scuba diver instructor and Matt hasn’t accompanied him to a single class ever, always excusing himself, BUT! That’s so small compared to the rest of the things. There would never be a single thing about Matt that could dissuade Shiro about considering him the love of his life. Not-a-single-one.

A shadow crosses his field of vision, distracting him from his thoughts. He is sure that something very fast moved past the coral reef there, but it’s too far. He is still considered a newbie, and never went farther than what Lance allowed him. But Lance is just entering the water… well, he’d be right behind him in a minute. Why not push the limits a bit?

He heads towards the coral reef and all the pretty fish scatter around. The view is gorgeous, but he tries to identify something similar to the shadow, to no avail. The thing, whatever it is, is big and fast… there weren’t sharks in those waters, right? Maybe it wasn’t such a great idea to dive so far. He can’t spot Lance around now, either. Damn, what had he done? He’d have to go to the surface and check there if…

Something moves again and this time he distinguishes the clear image of a tail heading to the darkness ahead, pass the coral reef. Without even considering the danger, like when he was a soldier, Shiro just follows the creature at full speed. But then he halts and almost forgets how to breathe.

It’s a mermaid. In the light waters of this quiet beach, at the very edge of the coral reef, a mermaid is struggling to untangle her hair from the pointy ends of it. The greenish scales of her tail shine with a litmus effect, subtly becoming paler around the waist, where her skin starts, so white it doesn’t look healthy. Her upper body is thin and quite small, like a child frame. Her long hair is light colored and it’s hopelessly hooked to the rough ends of the reef.

The beauty of the creature reminds him of that night when he had met Matt. Her appearance has the same effect in his body, freezing him on the spot. But then the mermaid looks at him with her huge, almond eyes and the resemblance enters uncanny valley realm, because the little creature looks EXACTLY like his boyfriend, her scared eyes have the same form and color as his.

Floating like a huge bag, Shiro tenses. After what feels like an eternity, he convinces his body to approach her, extending a hand to help her untangle her hair from the coral, when something pointy touches his neck. He looks to his left and finds a long harpoon of some sort ready to hurt him if he dared to move an inch. His eyes can’t see who holds it, but then he believes he hears the creatures communicate. He feels more than hears the vibration coming from the little one. And she is yelling “no, Matt!”

A pair of arms grabs him by the armpits and Shiro is being lifted, so shocked he can’t even breathe well. His head breaks the surface of the sea and he is blinded by the afternoon sun, while the person behind him is moving and splashing.

“Damn it, Shiro! Why did you have to run away?!” It was Lance, taking his gear away from his face to scold him, but Shiro just turns, taking off his mask and grabbing him by the arms.

“L-Lance! There are mermaids down there! Did you see?!”

“Buddy, calm down--”

“B-but she said...!” Shiro pauses and processes. He couldn’t be that mistaken, right? She had clearly said Matt. His mouth opens and he looks at Lance’s blue eyes, who in turn looks over Shiro’s shoulder. Wrinkling his face, he mutters:

“Well, shit.”

Shiro turns back and his eyes find the face he loves so much, in the middle of the sea, under the blazing sun. It’s Matt this time, but his… his body…

He looks mythical, like always, but his normally pale skin is now pure white, with a soft greenish tint, like the little mermaid he saw down there. His bony face is sharper, and his eyes bigger, but they have the same color and form as always. His wet hair covers his neck, but even so, Shiro can clearly see movement on its sides. Gills? What the hell?

Speechless, Shiro tries to understand what he sees. Then, to connect what he sees with reality. And then, it’s almost funny how so many of Matt’s weird habits are suddenly explained.

A merman. His boyfriend is a merman…

“Lance.” Matt’s voice is hoarser and deeper. “Can you give Pidge a hand? She’s stuck. I said we’ll have to cut her hair, but she didn’t let me touch her. Maybe you’ll have better luck.”

“R-right. I’m on it,” Lance replies, putting his oxygen mask on again and descending.

Silence falls between both of them, and Shiro can distinguish the fidgety attitude he usually finds so adorable in the man he loves.

“Uhm. So… Hi, babe,” Matt says, and tries to get closer. Shiro barely resists the urge to back away, but his face must be showing his shock, because Matt halts.

“I-I’m so sorry. I wanted to tell you, but I was so scared,” he blurts, fear in his voice painfully clear, “i-if you rejected me for being… like this… I don’t know… I just…”

Matt covers his face and Shiro feels a genuine sting in his chest. But he doesn’t even know where to begin.

“How can you even…?” he manages to ask.

“Some of us can shapeshift. When we’re really good, we can pass for humans. My… my family is very talented at it, we have been cooperating with humans for many generations… my dad did it before me too and then two years ago I was able to perfect the form, so… they sent me to work with the scientists from Altea College--”

“They KNOW?!” Shiro is shouting, but he can’t control his voice.

“Y-yeah, I help with their research, and they protect us. I can reach places they can’t. It’s been like this for decades, that’s why the campus specializes in marine investigation.”

Everything makes sense now. Why Matt never has any signal when he’s away… right, as if he could take his phone with him underwater. Why he never presented him to his parents, why he never took a scuba diving class… and maybe, why he was so interested in Shiro learning that skill with his friend’s classes.

“And… Lance also knows?” he asks, his tone hardening.

“Yes. He helped me when I started living on ground too...” Matt mumbles.

“So… I’m the only one who didn’t know. Your boyfriend. The only idiot who didn’t know.” Anger is bad and Shiro knows that, but he can’t control his hurt heart.

“No! Babe, please, you have to understand! How could I tell you after we met in that… that way? I never thought-- I wasn’t supposed to fall in love with a human…”

“God, Matt, what does that even mean? Are you saying you were always supposed to leave me someday and come back to the sea? Is that it?” Shiro is so hurt he isn’t sure if his face is only dripping sea water. 

“NEVER! I would never… please, you have to believe me!” Matt is now taking him by the shoulders and Shiro tries to brush him off. The merman panics.

“No, no, look at me. It’s me! It’s just me… Please…” Matt is transforming in front of his own eyes. He sees how the fingers clutching his shoulders separate, becoming thinner and the skin he loves so much to touch is back to its normal, soft and pale state. His arms surround his neck and a pair of legs cross around his body, gripping him as if he was afraid of drowning.

“I’m so sorry for not telling… I just love you so much…” the weak voice in his ear is breaking Shiro’s heart. He’s still mad, but… Matt didn’t _lie._ He omitted. That’s not the same, he tries to convince himself. Shiro ignores how long could merfolk survive away from the sea, but Matt spent entire weeks with him sometimes, always ending in a sudden urge to go and swim in the ocean he loves so much. He didn’t know until now, but there was a lot of sacrifice in every little thing Matt did for him, and now it was so... obvious. It finally explained so much. Besides, he couldn’t even deny he always thought no ordinary human could be so beautiful and pure as the man he had in front of him. Was he really… no, _could_ he even toss everything they had away for this?

The answer is still automatic. No fucking way in HELL he could be away from Matt Holt.

Shiro raises his hands and holds his boyfriend, missing touching that back, since his wetsuit covers him completely. Matt raises his face from his shoulder and his hands clutch Shiro’s face.

“I know I’m asking for a lot, but c-can you forgive me?” he begs, his eyes so red. “I’ll wait all the time you want, just--"

“No,” Shiro interrupts, “I… don’t think I really have to forgive you. I somehow understand _why_. I just…” he sighs, and takes Matt’s hands. “I love you so much I hate not knowing everything about you. I know this is the dumbest reason of all to be pissed, but--”

Matt kisses him desperately. The kiss has a salty taste, like every time they have kissed while swimming in the sea, but Shiro can still find in it the old sweet flavor he loves so much. Surprised by his own capacity to adapt and let go, he discovers he doesn’t feel any difference from before, now that he has been belatedly informed that he has kissed and, cough, _made love_ to a merman (goddammit he really did that _)_. In fact, this new secret identity thing makes him feel surprisingly relieved. Aside from explaining so much, he always thought that the mythical appearance of his boyfriend in his eyes was due to his smitten brain malfunctioning in a love overload or something. He wasn’t that crazy, after all.

“Oh god, and now you’re naked and I had to see your bits while ascending. What did I do to deserve this?”

The couple turn their heads and can see Lance a few meters away, floating and looking like he’d rather be anywhere else. A pair of big, almond eyes are by his side, looking at them with a guilty expression. The rest of the face is underwater.

“Pidgey! Are you ok?” Matt swims closer, a bit awkwardly with his human limbs, to the small head, that now is surfacing. The little mermaid’s hair is now short and a bit uneven. She throws herself on Matt’s arms.

“I did what I could, but she almost harpoons me, why did you let that thing with her?!” Lance scolds his friend, who mutters an apology.

“Who… is she?” Shiro asks, still amazed at the resemblance. He’s sure he knows the answer.

“Ah, right. Uhm. So… Takashi, this is my sister, Pidge. Say hi, Pidgey.”

She looks at him, as if she was assessing his face.

“...Hi. He’s cute, you were right,” says the mermaid in a weird voice. Like Matt before, she sounds hoarse outside the water. Matt blushes profusely.

“Hey! Shouldn’t you be apologizing for scaring him?” he grunts.

"You scared him," she replies, making a sarcastic face.

"Well-- yeah, because of you," his brother retorts, ashamed. Then, talking to Shiro, he adds:

“ _Smart_ mermaids never get too close to coral reefs, because this happens.” Matt takes one of his sister’s short locks, while she pouts. “She disobeyed and got too close to the beach. It’s dangerous, you could have been discovered AND you made me almost attack a human. Worse, it was Shiro. Mom and dad are gonna be so mad…”

“Sorry, but I couldn’t take it anymore,” she is still pouting, and Shiro finds it adorable. Cuteness runs strong in the family.

“Why? I told you I would present him to you when… well,” Matt looks a bit uncomfortable, but his sister suddenly makes a sassy face, almost devilish.

“No, I just wanted to check _them_ ,” she says.

“Check what?” asks Shiro and Matt is suddenly trying to cover his sister’s mouth, but she avoids him and wiggles her thin, greenish eyebrows.

“The most amazing, gorgeous, perfect, dreamy legs humankind has ever produced! That’s how he calls them…”

“PIDGE!!!”

Shiro feels himself blush. He can’t help remembering the stunned look Matt had that night they met. Did he feel flattered or just utterly ashamed?

“Oooookay, I’m out. Bye, weirdos.” Lance starts heading towards the shore, but then stops and points at Pidge. “And, for the record, the ‘most amazing legs’ title is MINE. Don’t listen to your dumb brother anymore... No offense, Shiro.”

“Sorry, I already witnessed the true champion, your noodle legs don't stand a chance,” answers the mermaid, swimming towards the offended instructor, laughing and splashing him on the way.

Matt and Shiro watch them for a while, then the merman turns to his partner, swimming back to his arms.

“Well. This was an absolute disaster,” he confesses.

“Yeah. But at least I met my sister-in-law,” jokes Shiro, still a bit confused, but relieved to confirm that his feelings were even more solid than he thought. Matt blushes again.

“Thank you. Thank you so much for…” Matt sighs. He just hugs Shiro once again, like a child.

“It’s fine. Let’s go back home and talk.”

Matt smiles bitterly. He’s still scared.

“You sure you’re okay with a half fish entering your house?” he asks. Shiro blinks, looking at him.

“Well, about that. I live one block closer to the beach than you. I’m not an expert in merfolk issues, but… I’d say it’d be healthier for you if you just moved in with me. Just saying.”

Matt looks at him with wide open eyes, while Shiro’s heart beats out of control. He said it. Not _at all_ like he had planned, but… Matt’s mouth twitches as he curves his lips in a sweet, relieved smile.

“You are absolutely right, as always. Let’s head home at once, then.” He squeezes Shiro, and mutters in his ear. “Besides, I can’t wait to be _this_ naked there. You know how I hate pants…”

Shiro laughs. But then finds himself swimming back to the beach with excessive enthusiasm, given the circumstances. Who could blame him? He is officially just another victim of the merfolk love songs. And a willing one, honestly.

**Author's Note:**

> Shiro's a simple man, and I'm a simple author who loves Matt Holt a normal amount, meaning I'll stan him until the day I die. And of course next Halloween they're gonna be Mer-man and Barnacle Boy, because that's how these dorks roll.  
> I always welcome prompts in my [Tumblr.](http://www.silverineontherun.tumblr.com)  
> Thanks for reading!


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